In known prior art satellite communication systems, the downlink data channels (i.e., transmission of data from the satellite to the satellite terminal) typically utilized bandwidths on the order of 20 MHz or less. In such systems, due to the narrow bandwidth being utilized, there was no need to provide for equalization in the demodulator/modem portion of the receiver, as the amplitude and phase distortions of the components where substantially constant.
However, as the need for additional bandwidth in the downlink data channels of satellite communication systems becomes necessary in order for such systems to provide various applications (e.g., high internet access capability) to end users, there is also a need to provide equalization in the demodulator/modem portion of receiver channel of the system, as signal phase and amplitude distortions become significant over a wideband channel. This is due to the fact that when utilizing channel bandwidths on the order of 500 MHz, there is significant amplitude and phase variations across the channel. These amplitude and phase distortions must be negated and/or compensated for in order for proper receipt and demodulation of the incoming data signal.
Furthermore, these distortions must be compensated for in a cost effective manner, which does not result in the satellite terminal becoming a non-commercially viable product. For example, while standard coaxial cable is sufficient for use with narrow bandwidth systems, it suffers from the foregoing problems when utilized in a wide bandwidth system (e.g. 500 MHz). However, while cables having constant amplitude and phase distortion over such wide bandwidths exist, such cables cannot be utilized in a commercially viable product as the cost of such cables is prohibitively expensive.
Accordingly, there exists a need for a cost effective method and apparatus for equalizing the incoming wideband data signal to compensate for amplitude and phase variations in the demodulator/modem portion of the receiver over the given bandwidth.